1. Field of the Invention:
The present invention relates to an opening/closing valve which makes it possible to open/close a fluid passage or a discharge passage, for example, for a pressure fluid or a gas.
2. Description of the Related Art
Conventionally, the machine for producing semiconductors such as semiconductor wafers and liquid crystal substrates is provided with a vacuum pump which is communicated and connected with a variety of process chambers via a passage which is constructed, for example, by a pipe and a valve. The passage is controlled to be opened/closed in accordance with the energizing/deenergizing action of the valve.
In general, the semiconductor-producing machine as described above is constructed, for example, by a film-forming apparatus and an etching apparatus each of which is provided with a heating unit including, for example, an unillustrated sheathed heater, in order to avoid any closure of the passage or any obstacle therefor which would be otherwise caused such that any product, which is formed in a vacuum chamber, adheres, for example, to the pipe and the valve at a temperature lower than the temperature of the vacuum chamber.
A thermostat or a thermocouple is used to control the temperature of a heating element which constitutes the heating unit. The temperature is controlled by controlling the current to be supplied to a heating member.
In such an arrangement, in the case of the thermostat, durability may not be satisfactory. On the other hand, in the case of the thermocouple, a control unit is expensive, and a great deal of cost is required for the equipment investment. Further, a large space is required as an installation space.
A general object of the present invention is to provide an opening/closing valve which makes it possible to reduce the production cost and which makes it possible to effectively utilize the installation space, by controlling the temperature with a simple structure.
The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example.